As a switch for processing a multicast cell, for example, Japanese patent application laid-open No. 9-162879 (1997) discloses a shared buffer type ATM. This ATM switch has address buffers provided for its output ports, respectively. The multicast is conducted by sequentially transferring the address pointer of a shared buffer where a multicast cell is stored. Also, the ATM switch needs to be provided with a counter for confirmation of the number of broadcast to be decremented every time a multicast cell is output.
However, the ATM switch has problems below.
The first problem is that it is necessary to provide a large amount of the buffer for multicast so as to cope with a case that the ratio of multicast cells in traffic increases.
The second problem is that it may cause the lowering of throughput since the subsequent multicast processing cannot be run before the counter for confirmation of the number of broadcast becomes zero.